Fluid pump or motor



March 2, 1943. p. s. COWHERD 2,312,961

FLUID PUMP OR MOTOR Filed Nov. 8, 1939 2 Sheets-Sheet l .7 Z. I i' I! a In l :i I 9 I INVENTOR 6 49 J J 4 x3 Dav/d .SfCowlzemf 7 2s v 26 v A TQRNE'Y March 2, 1943. D. s. COWHERD FLUID PUMP OR MOTOR Filed Nov. 8, 1959 2 SheetsSheet 2 INVENTOR Day/d 5. Cow/Yard.

Patented Mar. 2, 1943 UNITED STATES PATENT OFFICE FLUID PUMP on Moron David S. Cowherd, Kansas City, Mo. Application November 8, 1939, Serial No. 303,393 2 Claims. (01. 103-136) This invention relates to a fluid pump or motor and more particularly to one of rotary type, the principal objects of the invention being to provide a compact, relatively economical, convenient, and highly efficient device of that character.

Rotary fluid pumps or motors heretofore available have generally failed to meet the requirements placed on them, and it is believed that certain of the reasons for such failures lie in their lack of positiveness in drive and their tendency to leak as a result, for example, of complicated internal design and mechanisms. Internal back pressures, vibration in operation, excessive frictional contact of moving parts and other deleterious influences also ordinarily decrease the efiiciency of such heretofore available devices to such an extent that in practice they are of little value.

Other objects of the present invention are, therefore, to overcome the difliculties heretofore encountered in rotary fluid pumps or motors; to provide a rotary fiuid pump or mot-Jr that is positive and substantially fluid tight in practical operation; to provide for substantially equalizing internal pressures in devices of this character; to provide for substantially eliminating vibration and excessive frictional resistance in the fluid pumps or motors; and to prothem in a rotary fluid pump or motor of the character and for the purpose noted.

In accomplishing these and other objects of the present invention, I have provided improved details of structure, the preferred forms of which are illustrated in the accompanying drawings, wherein:

Fig. l is a perspective view of a rotary fluid pump or motor embodying the present in ention.

Fig. 2 is a detail vertical cross-section through the device illustrated in Fig. 1, particularly illustrating the relation between the stator, rotor, cam and blade elements thereof.

Fig. 3 is a detail horizontal cross-section substantially on the line 33, Fig. 2.

Fig. 4 is a detail perspective view of -my improved pump or motor showing a portion of the housing and a blade in disassembled relation to the stator and rotor respectively.

Fig. 5 is a detail vertical cross-sectional view through a modified form of pump or motor embodying this invention and particularly illustrating a valving arrangement for allowing circulation of fluid medium, the view illustrated being substantially on the line 55, Fig. 6.

steel material having a friction reducing finish on its inner wall forming face 2. Oppositely arranged spaced grooves or passages 3 and 4 initiate adjacent one end and on one face, Fig. 3, of the stator, which decrease in cross-sectional I area from their outer ends 6 and I toward their inner ends and merge gradually into the walls 2 at the end 8 of the stator to form a positive pressure area or chamber between the passages, later more particularly referred to.

A base 9, Figs. 1 and 4, is preferably provided for the stator, which may have apertures It to receive suitable fastening devices for securing the base to a primary support, not shown, the base preferably being fixed to the stator in supporting relation thereto by the connecting piece II, which may, if desired, be cast integrally with the stator.

Spaced annularly arranged apertures are provided in the stator for receiving fastening devices, such as the shanks of bolts l2, the headed ends l3 of which may engage the outer face of an annularly apertured housing plate 14 and the other ends of which may pass through similar apertures in a housing plate I5 to receive nuts for securing the housing plate 15 to the other side of the stator and thus form with the stator and plate H a housing for the stator and contents thereof.

The housing plate I4 is preferably provided with grooves I6 and I1 somewhat similar to and matable with the grooves or passages 3 and 4 in the stator, the grooves l6 and Il being provided by casting, for example, the plate It with channel forming bosses I8 and IS on the outer face thereof, Fig. 4, to provide sufficient depth for the grooves, the bosses preferably. being arranged in parallelism at their upper ends and the grooves l6 and I! continuing thereinto for forming interchangeable inlet and outlet ducts 20 and 2|, terminating in fittings 22 and 23 adapted to receive interchangeable supply and exhaust lines 24 and 25.

The outer face of the housing plate I4 is provided with an outwardly projecting preferably centrally arranged bearing boss 26 having the outer end thereof capped, as at 21, to retain a friction reducing bearing 28 in position adjacent a shoulder 29 in the plate. The inner face of plate I! is provided with a cam 30, preferably groove 32, the ends of which initiate adjacent the low lobe portion of the cam and increase inv depth at and toward their midportions at the high lobe portion of the cam.

A bushing 33 in the bearing opening of the cam supplemented by the bearing 28 directly rotatably supports a shaft 3|, preferably concentrically, in the housing plate H.

The shaft 34 has keyed thereto, as at 35, a rotor 36, preferably offset eccentrically relative to the inner wall of the stator in such a manner as to substantially contact, at its outer periphcry, a portion 31 of the inner wall of the stator and to substantially contact at its inner periphery a portion 38 of the cam. This provision provides spaces 39 and 40 of approximately equal crosssectional area between the inner and outer peripheries of the stator and rotor at the positive pressure chamber 8 of the housing and at the inner and outer peripheries of the rotor and cam opposite the positive pressure chamber 8. The

rotor has a flange 4|, by which it is keyed to the shaft and which substantially abuts a bearing 42 mounted on the shaft within the.housing side plate IS.

The plate I5 is provided with a bearing recess 43 to receive the outer periphery of .the rotor flange II and is also provided with a centrally bored bearing boss 44 to receive the bearing 42 and shaft 34. The outer end of the boss is provided with an inwardly directed annular shoulder 45 having an inner periphery of approximately the diameter of the shaft and seats packing 48 arranged about the shaft, a gland 41 being mounted, preferably threadedly, in the outer end of the boss for bearing against the packing to seal the housing.

The rotor is provided with spaced radially arranged slots 48 of suitable number depending on the size of the rotor, it being considered that the greatest possible number of slots consistent with adequate strength in the rotor is best.

Twelve slots, for example, have been found to be satisfactory in a rotor of four inch diameter.

Blades 49 are mounted in the slots, each of which preferably consists of a substantially rectangular body member of a length substantially equal to the distance between the outer periphery of the cam and the inner periphery of the stator. The outer ends of the blades are preferably curved, as at '50, Fig. 2, to substantially correspond to the curvature of the circumference of a circle having a diameter equal to the distance between the inner periphery of the stator and the outer periphery of the cam, whereby the blades always substantially contact the stator and compensate for variance in angles of contact caused by movement of the blades, the inner ends of the blades also preferably being curved, as at lit, for reducing friction due to contact with the cam. The blades are also preferably provided with notches 52 in their inner ends that are cooperative with the groove 32 in the cam for equalizing internal pressures in the housing by providing for transferring seepage of fluid between the rotor and blades throughout the system of the housing.

It has been found desirable to form the blades of a material different from the material of the cam and stator to thus reduce friction normally caused by the afflnity between like substances. The blades may also be provided. particularly at their ends, with friction reducing hardened surfaces.

While the blades have been shown with curvedsurfaces at their ends in relation to their thickness, it is believed apparent that the'ends of the blades may also be curved in relation to their width depending upon the particular shape of contact surfaces of the stator.

As a matter of practice and for increasing the efficiency of my improved pump or motor, the stator and a housing side plate are preferably provided with mating shoulders and recesses, as shown at 53, Fig. 3, for facilitating attachment of the plate to the stator, a gasket, such as paper, being applied between the outer contacting surfaces of the plate or plates and stator to additionally seal the interior of the housing.

The operation of my improved fluid pump'o'r motor is as follows:

Assuming the device is to be used as a pump, for example, a suitable prime mover is applied to the shaft for rotating the same. The interchangeable inlet and outlet ducts to the housing are respectively applied to a supply of fluid and a disposal device for the fluid and upon rotation of the shaft, the rotor rotates to move the blades. Assuming the duct 25 to be the inlet or supply duct, the blades create a suction thereon to draw fluid into the housing and through the passage 4 into the positive pressure chamber 8. Supply of fluid being constant and rotation of the rotor being maintained, all the fluid must follow in the path of the blades between the inner and outer peripheries of the stator and rotor, respectively, for transfer to the passage 3 and outlet 24 to the disposal device. At the positive pressure area 8 there is a minimum movement of the blades relative to the rotor and friction is thus minimized at the point of greatest pressure in the housing.

Small amounts of fluid seep between the blades into the interior of the rotor and where the fluid is oil, for example, there is an advantage from a lubrication standpoint. The seepage also fills the groove in the cam, the notches in the blades and the remaining space in the rotor interior to equalize pressure within the rotor on both sides of the positive pressure chamber 8 and thus decrease internal drag.

As the rotor rotates, the blades reciprocate therein from a point of minimum projection, as shown in Fig. 2, where the inner ends of the blades contact the low lobe portion of the cam to a point of maximum projection, where the inner ends of the blades contact the high lobe portion of the cam. A gradual application of increasing and decreasing blade surface area is therefore provided which serves to greatest advantage in first impositively acting on the fluid and then positively acting on the fluid while transferring the same from the inlet to the discharge portions of the pump.

When the device is used as a motor, fluid under pressure, admitted to the inlet passage of the housing acts on the blades to in turn act on the rotor to rotate the shaft. The shaft may thus be applied to a suitable driven mechanism for efficient actuation of the mechanism in response to supply and exhaust of fluid pressuremedium to the motor under control of conventional valves in one of the inlet and outlet lines.

A modified form of invention is illustrated in Figs. and 6, wherein a shaft 60 is rotatably mounted in a housing plate 6|, the shaft having a rotor 62 concentrically fixed thereto. A stator 63 is mounted between the plate BI and a plate 64 to form a housing, the plate 64 having an inwardly projecting bearing boss 65 arranged in eccentric relation to the shaft 60. The boss 65 is provided with a suitable friction reducing bearing 66 for rotatably supporting a cam 61 having an annular groove 68 to receive anchoring pins 69 on the inner ends of blades 10 mounted in radially arranged slots H in the rotor 62.

The stator 63 is of suflficiently greater inner diameter than the outer diameter of the rotor to provide for flow passages 12 and I3 to and,

from the housing and is preferably provided with a raised portion 14 intermediate the pasdirect fluid admitted to the housing from the inlet to the outlet of the housing in the manner of 'the preferred form of invention.

The valving mechanism is provided with an actuating device 19 on the upper end thereof to raise the shoe when desired, to permit circulation of fluid through the housing for, in effect, idling the pump or motor.

In operation, my modified form of invention is substantially similar to the preferred form thereof previously described, with the exception that centrifugal pull on the blades due to rotation of the rotor is controlled by the cam and friction is thus reduced between the blades and stator. The blades reciprocate in the rotor to present minimum and maximum eflective areas thereof relative to fluid in the housing for transferring the fluid from the inlet to the-outlet of the housing, whenthe device is used as a pump, and for rotating the shaft, when the device is used as a motor. When the device is to be idled; the, valve mechanism is actuatedto allow circu lation of fluid in the housing without discharge therefrom as by control of the outlet of the housing by conventional valves in the outlet line.

It is apparent, therefore, that a fluid pump or motor is provided by the present invention, of

compact, relatively economical, convenient and highly efficient character.

What I claim and desire to secure by Letters Patent is:

1. In a rotary fluid pump or motor, a housing, a shaft rotatably mounted in the housing, a rotor on the-shaft arranged within the housing, a cam in the housing arranged within the rotor, blades mounted in said rotor, fluid inlet and outlet passages in the housing so arranged that rotation of said shaft causes the blades to act on said passages to move fluid exposed thereto from one to the other thereof, and communicating cooperative means in said blades and cam respectively for equalizing internal fluid pressures in the rotor normally caused by flow of fluid into the interior of said rotor.

2. In an apparatus of the character described, a stator having inlet and outlet passages, a rotor rotatably mounted in the stator having a hollow space therein, a cam in the stator eccentrlcally mounted with respect to and within said hollow 35 space to have line contact with the periphery of said space at one point circumferentially thereof, said cam being coextensive with said space axially thereof, and blades in the rotor slidably engaged with the stator and cam, said blades 40 and cam having cooperative notches and a groove respectively for equalizing internal fluid pressures in the rotor. DAVID S. COWHERD. 

